Cyanosis is generally a late finding and usually does not occur until circulatory collapse and apnea are evident; particularly at the premorbid stage of cyanide toxicity. Initially the patient may experience flushing, tachycardia, tachypnea, headache, and dizziness. This may progress to agitation, stupor, coma, apnea, seizures, metabolic acidosis, pulmonary edema, bradycardia, hypotension, and death.